FIG. 1 depicts a portion of a conventional magnetic transducer 10, such as a conventional read transducer or other device. The conventional transducer 10 resides on a conventional substrate 11, such as an AlTiC substrate. The conventional transducer 10 includes a conventional bottom shield 12, conventional sensor 20, and conventional top shield 40. The transducer 10 also typically includes seed layer(s) (not shown) between the conventional AFM layer 22 and the conventional shield 12. The conventional shields 12 and 40 typically include NiFe and are formed by plating. The sensor 20 is shown in a current-perpendicular to plane (CPP) configuration. In a CPP configuration, read current is driven generally perpendicular to the plane of the layers of the device, along the z-axis shown.
The conventional sensor 20 includes a conventional antiferromagnetic (AFM) layer 22, a conventional synthetic antiferromagnet (SAF) 24, a conventional tunneling barrier layer 32, and a conventional free layer 34. Also shown is a conventional capping layer 36 for the conventional sensor 20. The conventional free layer 34 has a magnetization that is substantially free to change direction in response to an applied magnetic field, for example from a bit being read. The conventional tunneling barrier layer 32 may allow conduction through the sensor 20 via tunneling. The sensor 20 is thus a tunneling magnetoresistive (TMR) sensor. Note that if a conductive spacer layer is used instead of the barrier layer 32, then the sensor 20 is a spin valve. The conventional SAF layer 24 typically includes two ferromagnetic layers 26 and 30 separated by a nonmagnetic spacer layer 28. The ferromagnetic layers are generally antiferromagnetically coupled. The magnetization(s) of the conventional SAF layer 24 are pinned by the conventional AFM layer 22. More specifically, the first ferromagnetic layer 26, typically termed the pinned layer, has its magnetization pinned by the conventional AFM layer 22, for example via exchange interaction. The remaining ferromagnetic layer, or reference layer 30, has its magnetization pinned because it is strongly magnetically coupled with the pinned layer 26.
Although the conventional sensor 20 functions, the conventional transducer 10 may have limited utility. For example, conventional sensor 20 may be subject to noise. As recording densities increase, the read signal due to data recorded on the media may decrease. However, there may be no attendant reduction in the noise from the conventional sensor 24. The signal-to-noise ratio (SNR), the magnitude of the signal divided by the magnitude of the noise, may decrease. As a result, it may be difficult or impossible to correctly reading data from the media reliably using the conventional read sensor 20.
Accordingly, what is needed is a system and method for providing a read transducer having improved performance.